BODIES of extinct Ice Age mammals, such as woolly mammoths, that have been frozen in permafrost for thousands of years may contain viable sperm that could be used to bring them back from the dead, scientists said yesterday.

Research has indicated that mammalian sperm can survive being frozen for much longer than was previously thought, suggesting that it could potentially be recovered from species that have died out...

Mammoths, and other large mammals, only went extinct in North America when they were hunted to extinction by 12,000 years ago, just as soon as humans made it over the Bering. Mammoths, giant sloths, etc, are a natural part of our ecosystem and thus should be returned to the wild in North America.

wooly mamoths were not "ice age" animals. they were tropical animals like all elephants. The most famous of all mammoths, the frozen Berezovka mammoth, is displayed in the Zoological Museum in St. Petersburg, Russia, in the struggling position in which he was found near Siberias Berezovka River, just inside the Arctic Circle. His trunk and much of his head, reconstructed in this display, had been eaten by predators before scientists arrived in 1901. In 1977, the first of two complete baby mammoths was founda 612-month-old male named Dima. Several rhinoceroses have also been found. Other fleshy remains come from a horse,a young musk ox, a wolverine, voles, squirrels, a bison, a rabbit, and a lynx. Nikolai Vereshchagin, Chairman of the Russian Academy of Sciences Committee for the Study of Mammoths, estimated that more than half a million tons of mammoth tusks were buried along a 600-mile stretch of the Arctic coast. The mammoths hairy coat no more implies an Arctic adaptation than a woolly coat does for a sheep. The mammoth lacked erector muscles that fluff up an animals fur and create insulating air pockets. Neuville, who conducted the most detailed study of mammoth skin and hair, wrote: It appears to me impossible to find, in the anatomical examination of the skin and [hair], any argument in favor of adaptation to the cold. Long hair on a mammoths legs hung to its toes. Had it walked in snow, snow and ice would have caked on its hairy ankles. Each step into and out of snow would have pulled or worn away the ankle hair. All hoofed animals living in the Arctic, including the musk ox, have fur, not hair, on their legs. Fur, especially oily fur, holds a thick layer of stagnant air (an excellent insulator) between the snow and skin. With the mammoths greaseless hair, much more snow would touch the skin, melt, and increase the heat transfer 10100 fold. Later refreezing would seriously harm the animal. Skin. Mammoth and elephant skin are similar in thickness and structure. Both lack oil glands, making them vulnerable to cold, damp climates. Arctic mammals have both oil glands and erector musclesequipment absent in mammoths. Fat. Some animals living in temperate zones, such as the rhinoceros, have thick layers of fat, while many Arctic animals, such as reindeer and caribou, have little fat. Thick layers of fat under the skin simply show that food was plentiful. Abundant food implies a temperate climate. Elephants. The elephanta close approximation to the mammoth lives in tropical or temperate regions, not the Arctic. It requires a climate that ranges from warm to very hot, and it gets a stomach ache if the temperature drops close to freezing. Newborn elephants are susceptible to pneumonia and must be kept warm and dry. Hannibal, who crossed the Alps with 37 elephants, lost all but one due to cold weather. Water. If mammoths lived in an Arctic climate, their drinking water in the winter must have come from eating snow or ice. A wild elephant requires 3060 gallons of water each day. The heat needed to melt snow or ice and warm it to body temperature would consume about half a typical elephants calories. Unlike other Arctic animals, the trunk would bear much of this thermal (melting) stress. Nursing elephants require about 25% more water. Salt. How would a mammoth living in an Arctic climate satisfy its large salt appetite? Elephants dig for salt using their sharp tusks. In rock-hard permafrost this would be almost impossible, summer or winter, especially with curved tusks. Nearby Plants and Animals. The easiest and most accurate way to determine an extinct animals or plants environment is to identify familiar animals and plants buried nearby. For the mammoth, this includes rhinoceroses, tigers, horses, antelope, bison, and temperate species of grasses. All live in warm climates. Some burrowing animals are frozen, such as voles, who would not burrow in rock-hard permafrost. Even larvae of the warble fly have been found in a frozen mammoths intestinelarvae identical to those found in tropical elephants today. No one argues that animals and plants buried near the mammoths were adapted to the Arctic. Why do so for mammoths? Temperature. The average January temperature in northeastern Siberia is about -28°F, 60°F below freezing! During the Ice Age, it was much colder. The long, slender trunk of the mammoth was particularly vulnerable to cold weather. A six-foot-long nose could not survive even one cold night, let alone an eight-month-long Siberian winter or a sudden cold snap. For the more slender trunk of a young mammoth, the heat loss would be deadly. An elephant usually dies if its trunk is seriously injured. No Winter Sunlight. Cold temperatures are one problem, but six months of little sunlight during Arctic winters is quite another. While some claim that mammoths were adapted to the cold environment of Siberia and Alaska, vegetation, adapted or not, does not grow during the months-long Arctic night. In those regions today, vegetation is covered by snow and ice ten months each year. Mammoths had to eatvoraciously. Elephants in the wild spend about 16 hours a day foraging for food in relatively lush environments, summer and winter. Three Problems. Before examining other facts, we can see three curious problems. First, northern Siberia today is cold, dry, and desolate. Vegetation does not grow during dark Arctic winters. How could millions of mammoths and other animals, such as rhinoceroses, horses, bison, and antelope, feed themselves? But if their environment was more temperate and moist, why did it change? Second, the well-preserved mammoths and rhinoceroses must have been completely frozen soon after death or their soft internal parts would have quickly decomposed. Guthrie has written that an unopened animal continues to decompose long after a fresh kill, even in very cold temperatures, because its internal heat can sustain microbial and enzyme activity as long as the carcass is completely covered with an insulating pelt. Because mammoths had such large reservoirs of body heat, the freezing temperatures must have been extremely low. Finally, their bodies were buried and protected from predators, including birds and insects. Such burials could not have occurred if the ground were perpetually frozen as it is today. Again, this implies a major climate change, but now we can see that it must have changed dramatically and suddenly. How were these huge animals quickly frozen and buriedalmost exclusively in muck, a dark soil containing decomposed animal and vegetable matter? Muck. Muck is a major geological mystery. It covers one-seventh of the earths land surfaceall surrounding the Arctic Ocean. Muck occupies treeless, generally flat terrain, with no surrounding mountains from which the muck could have eroded. Russian geologists have in some places drilled through 4,000 feet of muck without hitting solid rock. Where did so much eroded material come from? What eroded it? Oil prospectors, drilling through Alaskan muck, have brought up an 18-inch-long chunk of tree trunk from almost 1,000 feet below the surface. It wasnt petrifiedjust frozen. The nearest forests are hundreds of miles away. Williams describes similar discoveries in Alaska: Though the ground is frozen for 1,900 feet down from the surface at Prudhoe Bay, everywhere the oil companies drilled around this area they discovered an ancient tropical forest. It was in frozen state, not in petrified state. It is between 1,100 and 1,700 feet down. There are palm trees, pine trees, and tropical foliage in great profusion. In fact, they found them lapped all over each other, just as though they had fallen in that position. How were trees buried under a thousand feet of hard, frozen ground? We are faced with the same series of questions we first saw with the frozen mammoths. Again, it seems there was a sudden and dramatic freezing accompanied by rapid burial in muck, now frozen. Clearly. mammoths did not live in the cold artic, but rather, a tropical one. For many more facts, see Frozen Mammoths

Theoretically possible given that the Mammoth and the Indian Elephant share the same ancestor; The problem however is that no usable sperm has been found as yet in frozen mammoth carcasses since the technology became available...

As far as the TRex goes, we may well build a very lifelike TRex robot in 100 years that "walks", "breathes", "eats", "defecates" and "urinates" (given our infatuation with dinosaurs this is almost inevitable as our technology advances - a "real" Jurassic Park of a sort, if you will); however, it will still just be a robot made out of space age materials and requiring some mighty fancy computer programs to keep it stable on just two feet.

But resurrecting a living TRex will not happen because dinosaur DNA is long gone. Now, genetically re-engineering an Ostrich or an Emu to (re)-grow teeth, and also claws on its "wings" and (re)-grow a longer tail, by finding a way to switch back "on" recessive genes governing these features (IF they exist and IF we can identify them) is more theoretically possible (if we are correct that these are descendants of theropod dinosaurs as most evidence now appears to indicate); however even such a scenario is still solidly within the realm of science fiction.

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